Eight hot dogs and seven hot dog rolls cost $13.60. Seven hot dogs and eight hot dog rolls cost $13.40. How much, in dollars, does a hot dog and a hot dog roll cost combined?
We can let a hot dog be H and a roll be R.
8H + 7R = $13.60
7H + 8R = $13.40
If we add the equations,
we get
15H + 15R = $27
that means that
H+R=$27/15
so the answer is 27/15.
+19 
